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Smruti K. Patel, Jorge Zamorano-Fernández, Carlie McCoy, and Jesse Skoch

OBJECTIVE

External magnetic forces can have an impact on programmable valve mechanisms and potentially alter the opening pressure. As wearable technology has begun to permeate mainstream living, there is a clear need to provide information regarding safety of these devices for use near a programmable valve (PV). The aim of this study was to evaluate the magnetic fields of reference devices using smartphone-integrated magnetometers and compare the results with published shunt tolerances.

METHODS

Five smartphones from different manufacturers were used to evaluate the magnetic properties of various commonly used (n = 6) and newer-generation (n = 10) devices using measurements generated from the internal smartphone magnetometers. PV tolerance testing using calibrated magnets of varying field strengths was also performed by smartphone magnetometers.

RESULTS

All tested smartphone-integrated magnetometers had a factory sensor saturation point at around 5000 µT or 50 Gauss (G). This is well below the threshold at which a magnet can potentially deprogram a shunt, based on manufacturer reports as well as the authors’ experimental data with a threshold of more than 300 G. While many of the devices did saturate the smartphone sensors at the source, the magnetic flux density of the objects decreases significantly at 2 inches.

CONCLUSIONS

The existence of an upper limit on the magnetometers of all the smartphones used, although well below the published deprogramming threshold for modern programmable valves, does not allow us to give precise recommendations on those devices that saturate the sensor. Based on the authors’ experimental data using smartphone-integrated magnetometers, they concluded that devices that measure < 40 G can be used safely close to a PV.

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Juan Maiguel-Lapeira, Ivan Lozada-Martinez, Daniela Torres-Llinás, Luis Rafael Moscote-Salazar, and Mohammed Al-Dhahir

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George A. Alexiou and Spyridon Voulgaris

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Alexandre Boutet, Aaron Loh, Clement T. Chow, Alaa Taha, Gavin J. B. Elias, Clemens Neudorfer, Jurgen Germann, Michelle Paff, Ludvic Zrinzo, Alfonso Fasano, Suneil K. Kalia, Christopher J. Steele, David Mikulis, Walter Kucharczyk, and Andres M. Lozano

OBJECTIVE

Historically, preoperative planning for functional neurosurgery has depended on the indirect localization of target brain structures using visible anatomical landmarks. However, recent technological advances in neuroimaging have permitted marked improvements in MRI-based direct target visualization, allowing for refinement of “first-pass” targeting. The authors reviewed studies relating to direct MRI visualization of the most common functional neurosurgery targets (subthalamic nucleus, globus pallidus, and thalamus) and summarize sequence specifications for the various approaches described in this literature.

METHODS

The peer-reviewed literature on MRI visualization of the subthalamic nucleus, globus pallidus, and thalamus was obtained by searching MEDLINE. Publications examining direct MRI visualization of these deep brain stimulation targets were included for review.

RESULTS

A variety of specialized sequences and postprocessing methods for enhanced MRI visualization are in current use. These include susceptibility-based techniques such as quantitative susceptibility mapping, which exploit the amount of tissue iron in target structures, and white matter attenuated inversion recovery, which suppresses the signal from white matter to improve the distinction between gray matter nuclei. However, evidence confirming the superiority of these sequences over indirect targeting with respect to clinical outcome is sparse. Future targeting may utilize information about functional and structural networks, necessitating the use of resting-state functional MRI and diffusion-weighted imaging.

CONCLUSIONS

Specialized MRI sequences have enabled considerable improvement in the visualization of common deep brain stimulation targets. With further validation of their ability to improve clinical outcomes and advances in imaging techniques, direct visualization of targets may play an increasingly important role in preoperative planning.

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David P. McMullen, Tessy M. Thomas, Matthew S. Fifer, Daniel N. Candrea, Francesco V. Tenore, Robert W. Nickl, Eric A. Pohlmeyer, Christopher Coogan, Luke E. Osborn, Adam Schiavi, Teresa Wojtasiewicz, Chad R. Gordon, Adam B. Cohen, Nick F. Ramsey, Wouter Schellekens, Sliman J. Bensmaia, Gabriela L. Cantarero, Pablo A. Celnik, Brock A. Wester, William S. Anderson, and Nathan E. Crone

Defining eloquent cortex intraoperatively, traditionally performed by neurosurgeons to preserve patient function, can now help target electrode implantation for restoring function. Brain-machine interfaces (BMIs) have the potential to restore upper-limb motor control to paralyzed patients but require accurate placement of recording and stimulating electrodes to enable functional control of a prosthetic limb. Beyond motor decoding from recording arrays, precise placement of stimulating electrodes in cortical areas associated with finger and fingertip sensations allows for the delivery of sensory feedback that could improve dexterous control of prosthetic hands. In this study, the authors demonstrated the use of a novel intraoperative online functional mapping (OFM) technique with high-density electrocorticography to localize finger representations in human primary somatosensory cortex. In conjunction with traditional pre- and intraoperative targeting approaches, this technique enabled accurate implantation of stimulating microelectrodes, which was confirmed by postimplantation intracortical stimulation of finger and fingertip sensations. This work demonstrates the utility of intraoperative OFM and will inform future studies of closed-loop BMIs in humans.

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Charis A. Spears, Syed M. Adil, Brad J. Kolls, Michael E. Muhumza, Michael M. Haglund, Anthony T. Fuller, and Timothy W. Dunn

OBJECTIVE

The purpose of this study was to investigate whether neurosurgical intervention for traumatic brain injury (TBI) is associated with reduced risks of death and clinical deterioration in a low-income country with a relatively high neurosurgical capacity. The authors further aimed to assess whether the association between surgical intervention and acute poor outcomes differs according to TBI severity and various patient factors.

METHODS

Using TBI registry data collected from a national referral hospital in Uganda between July 2016 and April 2020, the authors performed Cox regression analyses of poor outcomes in admitted patients who did and did not undergo surgery for TBI, with surgery as a time-varying treatment variable. Patients were further stratified by TBI severity using the admission Glasgow Coma Scale (GCS) score: mild TBI (mTBI; GCS scores 13–15), moderate TBI (moTBI; GCS scores 9–12), and severe TBI (sTBI; GCS scores 3–8). Poor outcomes constituted Glasgow Outcome Scale scores 2–3, deterioration in TBI severity between admission and discharge (e.g., mTBI to sTBI), and death. Several clinical and demographic variables were included as covariates. Patients were observed for outcomes from admission through hospital day 10.

RESULTS

Of 1544 patients included in the cohort, 369 (24%) had undergone surgery. Rates of poor outcomes were 4% (n = 13) for surgical patients and 12% (n = 144) among nonsurgical patients (n = 1175). Surgery was associated with a 59% reduction in the hazard for a poor outcome (HR 0.41, 95% CI 0.23–0.72). Age, pupillary nonreactivity, fall injury, and TBI severity at admission were significant covariates. In models stratifying by TBI severity at admission, patients with mTBI had an 80% reduction in the hazard for a poor outcome with surgery (HR 0.20, 95% CI 0.04–0.90), whereas those with sTBI had a 65% reduction (HR 0.35, 95% CI 0.14–0.89). Patients with moTBI had a statistically nonsignificant 56% reduction in hazard (HR 0.44, 95% CI 0.17–1.17).

CONCLUSIONS

In this setting, the association between surgery and rates of poor outcomes varied with TBI severity and was influenced by several factors. Patients presenting with mTBI had the greatest reduction in the hazard for a poor outcome, followed by those presenting with sTBI. However, patients with moTBI had a nonsignificant reduction in the hazard, indicating greater variability in outcomes and underscoring the need for closer monitoring of this population. These results highlight the importance of accurate, timely clinical evaluation throughout a patient’s admission and can inform decisions about whether and when to perform surgery for TBI when resources are limited.

Open access

Ellen L. Air, Katie O. Orrico, Deborah L. Benzil, Alan M. Scarrow, James R. Bean, Catherine A. Mazzola, Linda M. Liau, James T. Rutka, and Karin M. Muraszko

Annual conferences, educational courses, and other meetings draw a diverse community of individuals, yet also create a unique environment without the traditional guard rails. Unlike events held at one's home institution, clear rules and jurisdiction have not been universally established. To promote the open exchange of ideas, as well as an environment conducive to professional growth of all participants, the leading neurosurgical professional organizations joined to delineate the expectations for anyone who participates in sponsored events. The One Neurosurgery Summit Taskforce on Professionalism and Harassment developed a foundational policy that establishes common expectations for behavior and a unified roadmap for the prompt response to untoward events. We hope that publishing this policy will inspire other medical organizations to establish their own meeting and conference policies. More importantly, we wish to bring greater attention to everyone's responsibility for ensuring a safe and respectful space for education, scientific debate, and networking during organized events.

Open access

Vincent C. Ye, Alexander P. Landry, Teresa Purzner, Aristotelis Kalyvas, Nilesh Mohan, Philip J. O’Halloran, Andrew Gao, and Gelareh Zadeh

BACKGROUND

Adult brainstem gliomas are rare entities that demonstrate heterogeneous biology and appear to be distinct from both their pediatric counterparts and adult supratentorial gliomas. Although the role of histone 3 mutations is being increasingly understood in this disease, the effect of isocitrate dehydrogenase (IDH) mutations remains unclear, largely because of limited data.

OBSERVATIONS

The authors present the case of a 29-year-old male with an IDH1-mutant, World Health Organization grade III anaplastic astrocytoma in the dorsal medulla, and they provide a review of the available literature on adult IDH-mutant brainstem glioma. The authors have amassed a cohort of 15 such patients, 7 of whom have survival data available. Median survival is 56 months in this small cohort, which is similar to that for IDH wild-type adult brainstem gliomas.

LESSONS

The authors’ work reenforces previous literature suggesting that the role of IDH mutation in glioma differs between brainstem and supratentorial lesions. Therefore, the authors advocate that adult brainstem gliomas be studied in terms of major molecular subgroups (including IDH mutant) because these gliomas may exhibit fundamental differences from each other, from pediatric brainstem gliomas, and from adult supratentorial gliomas.

Open access

Koji Shiomi, Yoshiki Arakawa, Sachiko Minamiguchi, Haruki Yamashita, Yukinori Terada, Masahiro Tanji, Yohei Mineharu, Katsutsugu Umeda, Megumi Uto, Junko Takita, Hironori Haga, Takashi Mizowaki, and Susumu Miyamoto

BACKGROUND

Tumors in the pineal region consist of various histological types, and correct diagnosis from biopsy specimens is sometimes difficult. The authors report the case of a patient with a mixed germ cell tumor infiltrating into the pineal gland despite showing no elevation of tumor markers.

OBSERVATIONS

An 18-year-old man complained of headache and nausea and showed disturbance of consciousness. Magnetic resonance imaging showed hydrocephalus associated with a cystic pineal tumor. The patient underwent tumor biopsy followed by endoscopic third ventriculostomy for hydrocephalus in a local hospital. A pineocytoma was diagnosed, and the patient was referred to the authors’ hospital for treatment. Concentrations of placental alkaline phosphatase, alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin in cerebrospinal fluid were not elevated. However, the authors’ review of the tumor specimen revealed some immature cells infiltrating the pineal gland. These cells were positive for AFP, Sal-like protein 4, and octamer-binding transcription factor 3/4; and the diagnosis was changed to mixed germ cell tumor. Chemoradiotherapy was initiated, followed by surgical removal of the residual tumor.

LESSONS

Careful examination of all tumor specimens and immunohistochemical analyses are important for accurate diagnosis of pineal tumors.

Open access

Daisuke Sakai, Masato Tanaka, Jun Takahashi, Yuki Taniguchi, Jordy Schol, Akihiko Hiyama, Haruo Misawa, Shugo Kuraishi, Hiroki Oba, Yoshitaka Matsubayashi, So Kato, Ryo Sugawara, Masato Sato, Masahiko Watanabe, and Katsushi Takeshita

OBJECTIVE

For instrumented correction surgery for adolescent idiopathic scoliosis (AIS), surgeons are increasingly switching from titanium (Ti) alloy rods to stiffer cobalt-chromium (CoCr) rods. The authors conducted the first multicenter randomized controlled clinical trial to investigate whether these materials affect the outcomes in terms of spine correction and quality of life (QOL). This trial was registered at UMIN Clinical Trials Registry on September 3, 2012, under the identifier UMIN000008838 (level of evidence 1).

METHODS

Female AIS patients (Lenke types 1–3, patient age 10–19 years) were recruited at 5 Japanese institutions and randomized into two cohorts: 6.0-mm-diameter Ti rods were placed in one group, and 6.0-mm-diameter CoCr rods were placed in the other. Patients were followed up at 2 weeks and 3, 6, and 12 months with radiographic examination to quantify the sagittal and coronal correction (Cobb angle, thoracic kyphosis, rib hump, and apical vertebral rotation). Patients completed questionnaires (Scoliosis Research Society–22r, 12-Item Short-Form Health Survey, and Scoliosis Japanese Questionnaire–27) at 6 and 12 months to assess QOL.

RESULTS

A total of 69 AIS patients were randomized to the demographically similar Ti (n = 37) or CoCr (n = 32) cohort. Four adverse events were recorded, two in each cohort, but these were not related to the rod material. At the final follow-up, both Ti and CoCr cohorts showed significant improvement in spinal correction, including the Cobb angle, thoracic kyphosis, and rib hump size. The correction rates were 68.4% and 67.1% for the Ti and CoCr cohorts, respectively. No parameters differed significantly between the cohorts at any time. Survey data showed improved but similar outcomes in both cohorts.

CONCLUSIONS

Both treatments (Ti and CoCr) produced similar results and were efficient in engendering clinically significant spine corrections.

Clinical trial registration no.: UMIN000008838 (UMIN Clinical Trials Registry)